1. Field of the Invention
The present invention relates to an optical waveguide interconnection board particularly suited for use in a photoelectric multifunction board, to a method of manufacturing the same, to a precursor for use in manufacturing optical waveguide interconnection board, to a photoelectric multifunction board including such an optical waveguide interconnection board, and to a method of manufacturing the same.
2. Description of the Related Art
In IC or LSI technology, attention has recently been drawn to optical interconnections being used between devices, between boards inside equipment, or within a chip to improve operating speed or degree of integration in place of high-density electric wiring. Optical interconnections in high-speed, large-capacity, optical-communication systems use electronic devices to process the transmitted optical signals and thus need photoelectric multifunction devices.
For example, Japanese Patent Application Laid-Open (JP-A) No. 2003-114365 discloses an optical path-changing device for forming optical interconnections, that includes: an array-type photoelectric conversion unit having photoelectric conversion elements; an array-type optical waveguide unit having optical waveguides which have different lengths and each of which has at least one cut end having an angle of 45° with respect to the plane of the optical waveguide and serving as a mirror; and an optical waveguide for optically coupling one of the photoelectric conversion elements and one of the optical waveguides.
In recent years, the development of mobile instruments with radio-communication functions has been significant, and attempts have been made to replace a part of their electric connections with optical connections. Optical connections offer high speed and absence of electromagnetic induction, and are meant to address the problems of electromagnetic interference (EMI) from electric boards, low resistance against radio wave intrusion from outside, or signal irregularity (SI) caused by an incomplete connection.
For example, JP-A No. 2003-131081 discloses optical connection of a photoelectric multifunction board that includes a laminate of an optical waveguide board and an electric circuit board, and an optical device such as a light-emitting device or a light-receiving device. An electric chip including an optical pin and the optical device is used in the optical connection, and the optical pin is inserted into a guide hole in the optical waveguide board. JP-A No. 2003-57468 discloses a photoelectric multifunction board that includes an electric circuit board, an optical waveguide sheet, and an optical device (light-emitting or—receiving device) equipped with an optical path-changing means and embedded in the core portion of the optical waveguide sheet. The optical waveguide sheet with the optical device embedded therein is laminated on the electric circuit board.
However, none of the array-type optical waveguide unit, the optical waveguide board, and the optical waveguide sheet as disclosed in JP-A Nos. 2003-114365, 2003-131081 and 2003-57468 has a pre-installed means for changing the travelling direction of light therein. In particular, there is no disclosure concerning an element for changing the direction of light in a plane parallel to the surface of the optical waveguide or the optical waveguide sheet.
The photoelectric multifunction board disclosed in JP-A No. 2003-57468 uses an optical waveguide sheet rather than an optical waveguide line. In such a case, although the optical waveguide sheet needs no special processing, the optical device equipped with an optical path-changing means is large in size, and thus a significantly higher degree of integration cannot be expected from such a device. Additionally, different types of optical path changes require different types of devices having an optical path-changing means. The optical waveguide sheet cannot focus light on the target of signal transmission and thus only a part of the light can form signals to be transmitted. Therefore, the energy efficiency is very low, and then it is necessary to increase the amount of light emission from the light-emitting device, which shortens the life of the device.
Thus, there have been needs for: an optical waveguide interconnection board which has a light direction-changing element within a patterned optical circuit and can form highly integrated optical connections; a method of manufacturing the same; a photoelectric multifunction board; a method of manufacturing the same; and a precursor for use in manufacturing the optical waveguide interconnection board.